1. Technical Field
This document relates to devices and methods for the treatment of heart conditions such as valvular stenosis. For example, this document relates to devices and methods by which a guide catheter can align itself with a blood flow stream to thereby help direct a guidewire or other elongate device transmitted from the guide catheter through an orifice of a heart valve, or any other normal or abnormal passage in the body against the direction flow. This device can also be used to localize and repair leaks where a fluid flow jet is present in submerged or fluid-filled chambers.
2. Background Information
Cardiac valvular stenosis is a condition in which the heart's valves are narrowed (stenotic). With valvular stenosis, the tissues forming the valve leaflets become stiffer, narrowing the valve opening, and reducing the amount of blood that can flow through it. If the stenosis is mild, the overall cardiac output remains normal. However, when the valves can become severely stenotic, that can lead to a reduction in cardiac output and impairment of heart function.
Mitral valve stenosis is an abnormal narrowing of the mitral valve, resulting in a restriction of the blood flow from the left atrium to the left ventricle. The atrium heart chamber may enlarge as pressure builds up. Blood and fluid may then collect in the lung tissue (pulmonary edema), making it hard to breathe. Mitral valve stenosis can make a person severely short of breath, among other problems.
Aortic valve stenosis occurs when the heart's aortic valve narrows. When the aortic valve is so obstructed, the heart has to work harder to pump blood to the body. Eventually, this extra work limits the amount of blood the heart can pump, and may weaken the heart muscle. The left atrium may enlarge as pressure builds up, and blood and fluid may then collect in the lung tissue (pulmonary edema), making it hard to breathe. Medications can ease symptoms of mild to moderate aortic valve stenosis. However, the only way to treat severe aortic valve stenosis is by surgery to replace the valve.
Therapies to repair or replace the aortic valve include balloon valvuloplasty (valvotomy), surgical aortic valve replacement, and transcatheter aortic valve replacement (TAVR). TAVR involves replacing the aortic valve with a prosthetic valve that is delivered via the femoral artery (transfemoral) or the left ventricular apex of the heart (transapical). TAVR is sometimes referred to as transcatheter aortic valve implantation (TAVI).
One of the most challenging steps when performing a TAVR, valvuloplasty, or hemodynamic study on a stenotic aortic valve is to find the valve orifice and pass a guidewire, catheter, or other elongate medical device through this severely stenotic valve. The current practice involves random probing of the stenotic valve with the guide wire until the orifice is penetrated. The high-pressure jet of blood coming out of the narrowed valve makes it even more challenging to align a catheter and advance against the direction of flow. Prolonged probing increases the risk or dislodging small amounts of calcified debris and atheroma from the valve surface and can lead to strokes.